When handled improperly, or manufactured defectively, lithium-ion batteries are subject to thermal runaway i.e. the battery will spontaneously increase in temperature until it begins to vent hot pressurized gases. This eventually causes the battery to ignite, generating temperatures that can reach 2,000 degrees Fahrenheit. Because multiple batteries are often stored and packaged together during transport, thermal runaway of a single battery can ignite adjacent batteries. As is apparent, fires of this nature within the cargo hold of an aircraft have catastrophic potential.
It is known to use expanded glass as an aggregate within a panel to impart heat resistant characteristics. These panels employ resins or epoxy to bind the glass aggregate under high pressure. The panels are deficient for several reasons. First, they cannot withstand heat in excess of 400-600 degrees Fahrenheit which limits their application. The binders used in the prior art panels evaporate at that temperature resulting in structural failure of the panel.
In addition, prior art panels employ glass aggregate having a uniform size, typically the smallest size available, in an effort to impart rigidly to the panel. However, during manufacture of these panels, the high compression applied to the panel cause the binder to be forced into the air spaces of the small size glass aggregate which reduces the air content of the glass aggregate. The lower air content of the aggregate results in a panel having less heat resistance and no real capacity to handle temperatures of the type generated during a lithium-ion battery fire. Still other panels use a low grade Portland cement to bind the expanded glass aggregate. Although low grade Portland cement is non-combustible and more durable than epoxy or resin as a binder, long term fire exposure will eventually cause it degrade, resulting in panel failure.
A need has therefore existed in the art for a cementitious fire containment panel that overcomes the deficiencies of the prior art. The present invention provides a panel that is light in weight, possesses the flexural and tensile strength necessary for use in shipping containers or wall structures, yet is capable of withstanding temperatures in excess of 2,000 degrees Fahrenheit for sufficient periods of time.